What is the difference between Micro Etching and Macro Etching in
context to microstructure study?
i have a link
http://www.metprep.co.uk/history6_print.html
which discuss about Micro etch and macro etch? I am especially
interested in Al Alloys.
Thanks
Amit

Amit:
A typical definition is that macroetching is etching of a metal surface
to accentuate gross structural details such as grain flow, segregation,
porosity, or cracks for observation by the unaided eye or with a
microscope at magnifications of less than 25X or 50X. Microetching is
development of microstructure for observation with a microscope at
higher magnifications than 25X to 50X.
Typically macroetching is done on a ground surface while microetching
is done on a specimen which has been both ground and polished. Thus
microetching can be done with less concentrated and aggressive
chemicals than for macroetching.
Pittsburgh Pete
2007 2007 2007
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We do not believe what we write, and neither should you. Information
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Mark:
You are correct in pointing out that the preparation and etching must
be sufficient to remove the deformed surface resulting from sectioning
and grinding.
However, electropolishing or chemical polishing before etching is not
required to prepare aluminium before macroetching. For example, see
pages 35 and 36 of the LECO metallography guide available at:
http://www.leco.com/resources/application_note_subs/pdf/metallography/Met%20Principles%20and%20Procedures%20Catalog%20200-860.pdf
Pittsburgh Pete
2007 2007 2007
DISCLAIMER
We do not believe what we write, and neither should you. Information
furnished to you is for topical (external) use only. This information
may not be worth any more than either a groundhog turd, or what you
paid for it (nothing). The author may not even have been either sane or
sober when he wrote it down. Do not worry, be happy.

Mark:
You are correct in pointing out that the preparation and etching must
be sufficient to remove the deformed surface resulting from sectioning
and grinding.
However, electropolishing or chemical polishing before etching is not
required to prepare aluminium before macroetching. For example, see
pages 35 and 36 of the LECO metallography guide available at:
http://www.leco.com/resources/application_note_subs/pdf/metallography/Met%20Principles%20and%20Procedures%20Catalog%20200-860.pdf
Pittsburgh Pete
2007 2007 2007
DISCLAIMER
We do not believe what we write, and neither should you. Information
furnished to you is for topical (external) use only. This information
may not be worth any more than either a groundhog turd, or what you
paid for it (nothing). The author may not even have been either sane or
sober when he wrote it down. Do not worry, be happy.

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